Ice detector



y 1963 v. E. ADRIG 3,091,680

ICE DETECTOR Filed Oct. 28, 1960 3 Sheets-Sheet 1 EN TOR.

Vernon Hdrzlq aii'ys y 8, 1963 v. E. ADRIG 3,091,680

ICE DETECTOR Filed Oct. 28, 1960 3 Sheets-Sheet 2 Fig.5

J'NVENTQR. Vernon E Adrzy V E. ADRIG ICE DETECTOR May 28, 1963 3 Sheets-Sheet 3 Filed Oct. 28. 1960 a RIMJ 5 Q E mm U a H Y M .I Q g a QQ\ QR V N w #1 ME P QSN 7 Q3/ NEE h 9| Qm. Q N s M g g at ll. YE IQ e T fi; N8 1 g \d w United States Patent Ware Filed Oct. 28, 1960, Ser- No. 65,624 4 Claims. (Cl. 219-19) This invention relates to devices for detecting the formation of ice on equipment which is subject to icing conditions, and for energizing a heater which will remove the ice from the equipment so that the ice will not cause the equipment to malfunction. Such ice detectors are valuable for use on outdoor electrical switching gear, for example.

One object of the present invention is to provide a new and improved ice detector which is especially well adapted for use on static or stationary equipment.

A further object is to provide a new and improved ice detector having a moving element which is adapted to be stalled by the formation of ice thereon, the ice detector being provided with means for producing a control signal in response to the stalling of the movable element.

Another object is to provide a new and improved ice detector of the foregoing character in which the moving element takes the form of a rotor driven by a slip clutch, and in which a switch is operated in response to any slipping of the clutch due to the stalling of the rotor by the formation of ice thereon.

A further object is to provide a new and improved ice detector of the foregoing character, in which the slip clutch comprises two magnets, one of which is caused to move toward and away from the other magnet when slippage occurs in the clutch, such movement of the first magnet being employed to operate the switch.

It is another object to provide a new and improved ice detector which is extremely small and compact, yet is highly dependable in operation.

A further object is to provide a new and improved ice detector of the foregoing character, having a heater which is energized for a limited time when the movable element of the ice detector is stalled, so as to free the movable element for another cycle of operation.

Another object is to provide a new and improved ioe detector having means for protecting the ice detector itself from moisture and freezing conditions.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a plan view of an ice detector to be described as an illustrative embodiment of the present invention.

FIG. 2 is an elevational view of the ice detector of FIG. 1.

FIG. 3 is an enlarged, somewhat diagrammatic elevational section, taken generally along a line 3-3 in FIG. 1.

FIG. 4 is a plan view of one of the ring-shaped magnets employed in the ice detector.

FIG. 5 is a schematic diagram showing the electrical circuit for the ice detector.

As already indicated, the drawings illustrate an ice detector comprising a probe 12 having a movable element or member 14 and a stationary element or member 16. The movable member 14 is adapted to move adjacent the stationary member 16, but is adapted to be stalled by the formation of ice between the members 14 and 16. In FIG. 2, a coating of ice 18 on the members 14 and 16 is illustrated in broken lines. It will be apparent that the ice 18 will interfere with the movement of the member 14 if the ice becomes sutiiciently thick. In this case, the movable member 14 takes the form of a generally hook- 3,091,680 Patented May 28, 1963 ice shaped rotor, while the stationary element 16 is in the form of a cylinder or sleeve around which the rotor 14 is movable. The sleeve 16 projects outwardly from a small casing 20 which in turn is mounted on a larger casing 22. Apertured flanges 24 may be provided on the casing 22 for use in mounting the casing on the equipment to be protected by the ice detector. The smaller casing 20 and the probe 12 may conveniently be arranged to project through an opening in a wall of the equipment to be protected.

As shown to advantage in FIG. 3, the hook-shaped rotor 14 has a straight shaft portion 26 which is rotatable within the stationary sleeve member 16. The rotor 14 has an arm portion 28 which extends radially from the shaft portion 26 and then doubles back toward the sleeve member 16. It will be seen that the arm 28 has an end portion 30 which is substantially parallel to the sleeve member 16 and is rotatable in closely spaced relation to the sleeve member. Thus, the formation of a relatively thin layer of ice on the sleeve member or the end portion 30 of the rotor 14 will interfere with rotation of the rotor and thus will tend to stall the rotor.

It will be seen that the sleeve member 16 comprises a cylindrical outer shell 32 which is welded or otherwise secured to the casing 20. A bushing 34 is received within the shell 32. It will be seen that the bushing 34 has an enlarged lower portion 36 which is disposed within the casing 20.

The shaft 26 of the rotor 14 is journalled within the bushing 34. In the illustrated construction, the lower end of the shaft 26 is screwed into an internally threaded longitudinal bore 38 in a cylindrical shaft extension 40. A ball-bearing 42 may be provided to support that lower end of the extension 40. As shown, the ball-bearing 42 is mounted on a pin 44 projecting upwardly from a plate or partition 46 which separates the casing 20 from the casing 22. By virtue of this arrangement, the rotor 14 is freely rotatable relative to the casing 20, in the absence of ice between the rotor and the sleeve member 16.

To exclude moisture from the casing 20, a rotary shaft seal 48 is provided around the shaft extension 4%. In this case, the seal 48 comprises a rotatable ring 5t) which is in rotary sealing engagement with a stationary ring 52. The ring 50 may be made of metal, while the ring 52 may be made of a material containing graphite, so as to be selflubricating. A soft rubber or rubbe-like sealing ring 54 is provided between the ring 52 and a cavity or recess 56 in the enlarged portion 36 of the bushing 34. Similarly, soft rubber-like sealing ring 58 of C-shaped cross section is provided between the ring 50 and a flange member 61) secured to the shaft extension 49. A compression coil spring 62 provides pressure between the ring 50 and the ring 52.

An electric heater is provided to melt the ice from the probe 12 so as to free the rotor 14 for another cycle of operation, after the rotor has been stalled by the formation of ice thereon. In this case, the rotor 14 is in the form of a tubular outer shell 64. An electrical resistance type heating element 66 is received within the tubular shell 64. The outer end of the heating element 66 may be connected to the shell 64, which may be made of metal so as to serve as one terminal of the heating element. The shell 64 is grounded to the casing 20 through the bushing 34.

As shown, the inner end of the heating element 66 is brought out by a lead 68 which may be connected to a slip ring 70 mounted on the flange 60. As shown, the slip ring 70 is engaged by a brush 72, which thereby is adapted to supply electrical energy to the heating element 66. A suitable terminal 74 may extend through the partition 46 into the casing 22 from the brush 72.

A heating element 76 may also be provided to melt ice from the sleeve member 16. As shown, the heating element 76 is mounted in a helical groove formed in the outside of the bushing 34. One end of the heating clement 76 may be grounded. and the other end ma be brought out by means of a lead connected to a crrninal 82 which extend; through the partition 3 T feedthrough terminals '74 and 83 are insulated and inctically sealed so as to exclude moisture from the casin To assist in excluding moisture from the casing 20., heating element 36 may be mounted on the inside of the wall of the casing 20. The heating element 56 may be controlled by a suitable thermostat so a; to maintain the temperature within the casing 2t above the freezing 17,.IHL.

An electric motor 90 is provided within the casing 22 for driving the rotor 14. The motor 9d has a drive shaft 92 which is secured within a longitudinal bore M in a drive shaft extension 96. The motor 90 is preferably provided with self-contained gears (not shown) so that the drive shaft 92 will be rotated at a slow speed, such as twelve revolutions per minute, for exampic.

The drive shaft extension Q6 is coupled to the rotor 14 by means of a slip clutch 98 which delivers only a hm ted amount of torque to the rotor 14. Under normai conditions. the torque is suthcient to rotate the rotor 14 without any slipping of the clutch 98. However, the fo n. "on of ice on the rotor 14 or the sleeve member M will stall or slow down the rotor 14, so that the cirtch will "13. A switch 100 is arranged to be operated by any slip of the clutch 98. Thus, the switch 100 may be cennc in an electrical circuit to provide a control signal in sponse to the formation of. ice on the probe 12. This control signal may be employed to operate a h .cr or other de-icing equipment for removing the ice from the apparatus protected by the ice detector. The control signal may also be employed to energize the probe heaters 66 and 76 for a limited time, so as to free the rotor 1'"! for another cycle of operation.

in this case, the slip clutch 98 compri'cs two perm nent magnets 102 and 104. which are substantially ringshaped, as shown in FIGS. 3 and 4. The riiy' ahapsd magnets 102 and 104 are magnetized with alternate north and south poles, as indicated in FIG. 4. As shown. the magnet 1.02 is presed onto or otherwise secured to the lower end of the rotor shaft extension 40. The ma 104 is pressed into or otherwise secured in a circular recess or bore 106 formed in a flange 108 which extends outwardly from a supporting member or hub 110. in this case. the hub 110 is formed with a bore 112. which is slidably received over the drive shaft extension $6. A pin 114 is provided to connect the hub 110 to the drive shaft extension 96 so that the hub will rotate with the drive shaft extension. However. the pin 114 is slidably received in a longitudinal slot 116 in the extension 96. to that h b 110 will be free to slide back and forth through a limited range along the extension 96.

It will be seen that the magnets 102 and oppo ite sides of the partition 46 between the c. and 22. Torque is transmitted between the magne and 102 by virtue of the magnetic field between the ir f nets. When the rotor 14 is free to rotate. the man. ts 102 and 104 align themselve so that magnetic poles cf opposite polarity are opposite each other on t e two magnets. Thus the magnets 102 and E04 are strongly attracted to each other so that no slippage occurs between the magnets. Moreover, the magnet 104 is attracted toward the magnet 102, so that the magnet 104 is held against sliding movement along the drive shaft extension 96.

When the rotor 14 is slowed down or stalled by the formation of ice between the rotor and the sleeve mem ber 16, slippage occurs between the magnets 102 and 104. The slippage causes alternate attraction and repulsion between the magnets 102 and 104, as the poles of the magnet 104 move past the poles of the magnet 162. Thus,

the magnet 104 and the hub are moved back and forth along the shaft extension 96.

It will be seen that the control switch 100 comprises a pair of normally open contacts 120 and 122 which are mounted on spring arms 124 and 126. An operating arm 128 is also provided to close the contacts 120 and 122 when the hub 110 is moved back along the shaft extension 96 by the repulsion between the magnets 102 and 104. The arm 128 has an end portion 130 which is engageable by the flange 108 on which the magnet 104 is mounted. Thus, the switch 100 is closed when slippage occurs between the magnets 102 and 104 of the slip clutch 98. The closure of the switch 100 indicates that ice has formed on the rotor 14 to an extent sufficient to stall the rotor.

As already indicated, the closure of the switch 100 may be employed to produce a signal which energizes the probe heaters 66 and 76 for a limited time, so as to free the rotor 14 for rotation, so that the ice detector will go through another cycle of operation. The ice detector is also arranged to supply an output signal of a particular duration which can be used to energize heaters, relays or other equipment. Thus, the detector may be employed to energize an external heater or other deicing apparatus adapted to remove the ice from the equipment protected by the ice detector. These functions may be carried out by the electrical arrangement shown in FIG. 5.

The ice detector may be energized by alternating current received from a pair of power lines 142 and 144. The alternating current may be at 110 volts and 60 cycles, or any other suitable voltage and frequency. A thermostatic switch 146 may be employed to start the ice detector when the atmospheric temperature drops to such an extent that icing conditions can occur. The thermostatic switch 146 is effective to shut down the ice detector when the atmospheric temperature rises to a level such that icing conditions cannot occur. It will be seen that the thermostatic switch 146 is connected between the power line 144 and a lead 148. The drive motor 90 is connected directly between the leads 142 and 148, so that the drive motor is energized whenever the thermostatic switch 146 is closed.

The switch 100 may be employed to operate a relay 150 having a coil or winding 152. Direct current to operate the relay 150 may be provided by a full wave rectifier 154 having input leads 156 and 158 connected to the alternating current power leads 142 and 148. The direct current from the rectifier 154 may be delivered across direct current power leads 160 and 162. It will be seen that the control switch 100 is connected between the direct current lead 162 and a lead 164 extending to one side of the relay coil 152. The other side of the relay coil 152 is connected to the direct current power lead 160 by a normally closed timer switch 166. Thus, the closure of the control switch 100 energizes the relay coil 152.

To maintain the energization of the relay coil 152, the relay 150 is provided with a pair of holding contacts 168 which are connected across the switch 100. The holding contacts 168 are normally open but are closed when the relay coil 152 is energized. This completes a holding circuit which bypasses the switch 100, so that the relay coil 152 Will continue to be energized, even if the switch 100 is opened. The energization of the relay coil 152 continues until the timer switch 166 is opened by a timer 170.

The timer 170 may be of any known or suitable type, and is adapted to be energized or started by the closure of another pair of normally open contacts 172 on the relay 150. One side of the timer 170 is connected to the direct current power lead 160, while the other side of the timer is connected to the power lead 162 through the contacts 172. After being energized for a predetermined interval, the timer 170 opens the switch 166 and thereby de-energizes the relay coil 152. The relay coil 152 will remain de-energized until the control switch 100 is again closed.

The relay 150 has a third pair of normally open contacts 174 which control the energization of the probe heaters 66 and 76 and the external de-icing heater 140. Thus, one side of the heater 140 is connected to the alternating current power line 142. This is also true of one side of each of the probe heaters 66 and 76. Thus, the heaters 66, 76 and 140 are connected in parallel between the lead 176 and the alternating current power line 142. The contacts 174 are connected between the lead 176 and the alternating current power lead 148. Thus, closure of the contacts 174 energizes the heaters 66, 76 and 140.

The casing heater 86 is connected in series with a thermostatic switch 178 across the alternating current power leads 142 and 148. The thermostatic switch 178 maintains the temperature inside the casing 20 above the freezing point so that the operation of the ice detector will not be impaired by any moisture that may penetrate into the casing 20.

In operation, the rotor or vane 14 is normally rotated by the magnetic attraction between the permanent magnets 102 and 104 of the slip clutch 98. The permanent magnet 104 is continuously rotated by the motor 90 at a low speed. When ice forms to a sufiicient thickness on the rotor 14 or the sleeve member 16, the rotor will be slowed down or stalled so that slippage will occur between the permanent magnets 102 and 104. As a result, the permanent magnet 104 and its mounting hub 110 will be slid back and forth along the shaft extension 96 by the alternate repulsion and attraction between the magnets 102 and 104, as the poles on the magnets move past one another. As the magnet 104 moves away from the magnet 102, the flange 108 engages the switch operating arm 128 and closes the contacts 120 and 122 of the switch 100. Thus, the closure of the switch 100 indicates that ice has formed on the probe members 14 and 16 of the ice detector.

The closure of the switch 100 energizes the relay 150, which in turn energizes the timer 170. The encrgization of the relay 150 is maintained by the holding contacts 168 on the relay. The contacts 174 of the relay energize the probe heaters 66 and 76 and the external de-icing heater 140. After a limited time, the timer 170 opens the switch 166 so as to de-energize the relay 150. If the switch 100 is still closed, the relay 150 will again be energized, and the timer 170 will go through another cycle.

The heat generated by the probe heaters 66 and 76 melts the ice from the rotor 14 and the stationary sleeve 16. When the ice has been melted suflicicntly to free the rotor 14, the slip clutch 98 will again rotate the rotor without any slippage in the clutch. Thus, [the switch 100 will be opened. The rotor 14 will continue to rotate until it is again stalled by the formation of ice on the rotor or the sleeve member 16.

The external heater 140 may be located so as to melt the ice from the equipment which is protected by the ice detector. It will be apparent that the ice detector energizes the heater 140 only when icing conditions exist. Thus, the consumption of electrical power by the heater 140 is minimized.

A pilot lamp 180 may be connected between the alternetting current power leads 142 and 148 to indicate when the ice detector is turned on by the thermostatic switch 146. When the atmospheric temperature is above the level at which icing conditions can occur, the thermostatic switch 146 turns off the ice detector.

It will be apparent that the ice detector is effective in operation and extremely compact. Nevertheless it is low in cost and economical to operate.

Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

I claim:

1. In an ice detector, the combination comprising a probe having a stationary sleeve member, said probe comprising a rotary member having a shaft portion rotat able within said stationary sleeve member, said rotary member having a generally hook-shaped arm portion extending outwardly from said shaft portion and rotatable adjacent the outside of said sleeve member, said arm portion being adapted to be stalled by the formation of ice between said arm portion and said sleeve member, a magnetic slip clutch for driving said rotatable member, said clutch comprising a first permanent magnet mounted on said rotary member, a drive shaft, and a second permanent magnet adjacent said first permanent magnet and mounted on said drive shaft for rotation therewith and for limited axial sliding movement thereon, a motor for continuously rotating said drive shaft, a switch operable by sliding movement of said second permanent magnet relative to said drive shaft, said second permanent magnet being attracted toward said first permanent magnet and thus being held against sliding movement along said drive shaft as long as said rotary member is rotating, said second permanent magnet being caused to slide back and forth along said drive shaft by the alternate repulsion and attraction between said permanent magnets when said rotary member is stalled, an electric heater for heating said probe to remove ice therefrom, and means operable by said switch for energizing said electric heater for a predetermined interval so that said rotary member will be freed of ice after being stalled.

2. In an ice detector, the combination comprising a stationary probe member, a rotary probe member rotatable adjacent said stationary probe member and adapted to be installed by the formation of ice between said members, a motor, a slip clutch connected between said motor and said rotary probe member, a switch operable in response to slipping of said clutch when said rotary probe member is stalled, a heater for melting ice from said probe members, and means operable by said switch for energizing said heater for a limited time so as to free said rotary probe member from ice after being stalled.

3. In an ice detector, the combination comprising a stationary probe member, a hook-shaped rotor rotatable adjacent said stationary member, a heater within said rotor, a drive shaft, a motor for continuously rotating said drive shaft, a slip clutch connected between said drive shafit and said rotor for rotating said rotor with a limited torque, said rotor thereby being adapted to be stalled by the formation of ice between said rotor and said stationary member, said slip clutch comprising a first magnet carried by said rotor and a second magnet on said drive shaft, means mounting said second magnet on said drive shaft for rotation therewith and limited sliding movement along said drive shaft, said second magnet being attracted toward said first magnet and thereby being held against sliding movement as long as said rotor is being driven without slippage by said clutch, said second magnet being slid back and forth along said drive shaft by the alternate repulsion and attraction of said magnets when slippage occurs between said magnets, a switch operable by the sliding movement of said second magnet, and means operable by said switch for energizing said heater in said rotor for a limited time to melt the ice from said rotor and thereby free said rotor for another cycle of operation.

4. In an ice detector, the combination comprising a stationary probe member, a rotor rotatable adjacent said stationary member, a drive shaft, a motor for continuously rotating said drive shaft, a slip clutch connected between said drive shaft and said rotor for rotating said rotor with a limited torque, said rotor thereby being adapted to be stalled by the formation of ice between said rotor and said stationary member, said slip clutch comprising a first magnet carried by said rotor and a second magnet on said drive shaft, means mounting said second magnet on said drive shaft for rotation therewith and limited sliding movement along said drive shaft, said second magnet being attracted toward said first magnet and thereby being held against sliding movement as long as said rotor is being driven without slippage by said clutch, said second magnet being slid back and forth along said drive shaft by the alternate repulsion and attraction of said magnets when slippage occurs between said magnets, and a switch operable by the sliding movement of said second magnet.

References Cited in the file of this patent UNITED STATES PATENTS Ford July 4, Okulitch et al May 9, Hubbell Sept. 12, Okulitch et al. Sept. 4, Veldhuis Dec. 16,

FOREIGN PATENTS Great Britain June 6, France Feb. 23, 

2. IN AN ICE DETECTOR, THE COMBINATION COMPRISING A STATIONARY PROBE MEMBER, A ROTARY PROBE MEMBER ROTATABLE ADJACENT SAID STATIONARY PROBE MEMBER AND ADAPTED TO BE INSTALLED BY THE FORMATION OF ICE BETWEEN SAID MEMBERS, A MOTOR, A SLIP CLUTCH CONNECTED BETWEEN SAID MOTOR AND SAID ROTARY PROBE MEMBER, A SWITCH OPERABLE IN RESPONSE TO SLIPPING OF SAID CLUTCH WHEN SAID ROTARY PROBE MEMBER IS STALLED, A HEATER FOR MELTING ICE FROM SAID PROBE MEMBERS, AND MEANS OPERABLE BY SAID SWITCH FOR ENERGIZING SAID HEATER FOR A LIMITED TIME SO AS TO FREE SAID ROTARY PROBE MEMBER FROM ICE AFTER BEING STALLED. 